The present invention relates to a grid plate which is adapted to be used as a ground securing element for parking places, road embankments, ramps, etc., and which is constructed so as to interlock with adjacent grid plates using either the top or bottom of the grid plate as the tread side.
Grid plates made of synthetic material are known. As disclosed in OS-PS No. 29 40 236, the connection to adjacent already installed grid plate consists, for example, of one or several hook elements which project beyond two adjacent side walls of the grid plate. Catch parts at the other two sides of the grid plate, which have noses, are used for interlocking with the hook elements. The joints between one plate and an adjacent plate, which were created during the installation, are subsequently bridged or filled out by coupling elements to complete the installation operation. This requires an additional structural element and an additional work step. Further, this grid plate construction is not suitable for soft ground conditions and high loads.
In another known grid plate as shown in DT-PS No. 804 960, box-shaped rods are utilized to connect adjacent grid plates, which can be pushed into one another by a laterally arranged key and slot construction. In order to ensure proper alignment in the case of a possible load, the slot sides of each grid plate are pinned to the ground.
U.S. Pat. No. 3,836,075 shows a soil securing plate for the securing of garage driveways, etc. Each securing plate is provided with projecting plug-in elements which are adapted to be plugged into corresponding recesses in the opposite side of the grid plate. However, this securing plate can be installed only as a strip. When attempting to secure a large area of soil, one strip of plates cannot be interlocked with an adjacent strip of attached securing plates.
Another grid plate construction as described by EU-PS No. 0 117 707, provides a soil securing plate which can be installed by plugging all four sides of the plate together with the adjacent plates. During the installation operation, the requirement of such a connection arrangement is very time-consuming. In addition, the distances between the holes must be provided within certain tolerances in order to permit proper connection of adjacent plates.
As disclosed by DE-OS No. 33 27 867, a securing plate is provided with tooth tabs which project over all four sides, such that these tooth tabs are disposed at the same level as the plate surface and engage into gaps of an adjacent plate arranged in a sunk manner with respect to the surface. These plates are installed from above onto an already emplaced neighboring plate; however, no interlock is provided between adjacent plates in the upward direction, and thus this construction permits adjacent plates to become easily disconnected.
In another known plate construction as disclosed by U.S. Pat. No. 4 226 064, two sides of the plate disposed at a right angle with respect to one another are provided with hooks which point towards the bottom side of the plate. These hooks engage an adjacent plate via a gap extending to the ground which is provided at the two other sides of the plate. Other catch elements prevent an unlocking of connected plates, if lateral forces affect the ground covering; however a disassembling of such a ground covering is difficult to carry out.
Accordingly, it is the object of the present invention to provide a grid plate which can be readily emplaced so that an area secured by the grid plates of the present invention can be loaded with considerable vertical and horizontal forces without any detrimental effect, locks itself during the emplacement operation with the adjacent plate and can be unlocked again in a simple manner in case of need, which precludes a clogging up of the locked parts during the emplacement on loose soil, and which, by its special form, is simple and inexpensive to manufacture, and in which the upper side or the underside is be used as a tread.
In accordance with the present invention, a grid plate of plastic material is provided having a rough slippage-preventing top side and a rib-reinforced bottom side. The grid plate is adapted to be emplaced as a securing element for parking places, road embankments, ramps and the like.
The grid plate is three-dimensional and includes an upper face, a lower section opposite the upper face, and at least four sides around the perimeter extending from the upper face to lower section. Plug-in connecting means are provided and adapted to be locked together and again disconnectable for connecting together emplaced. The connection means include at least one insertable first connecting web means projecting out of a first side wall of the grid plate at given positions and extending substantially parallel to the upper face. The first connecting web means each have a free-end angularly bent hook-shaped into a half-hinge such that the free ends of the first connecting web means points in the direction towards the upper face of the grid plate. At least one insertable, second connecting web means is provided which projects out of a side wall which abuts the first side wall of the grid plate at given positions and extends substantially parallel to the upper face. The second connecting web means each has a hook-shaped free-end angularly bent into a half-hinge such that the free ends of the second connecting web points in the direction towards the lower section of the grid plate. Further, one horizontal wall aperture means are provided in each of the at least two side walls which do not include first and second web connecting means in positions on each of the side walls for engaging first and second connecting web means of adjacently arranged grid plates.
According to advantageous features of one embodiment of the present invention, and due to the positioning of the interlocking elements of the present invention in direct vicinity of the top surface of the grid plate, the functioning of these interlocking elements is not impaired when the ground is loose. This prevents clogging of an abutment for the connecting web means or of the wall aperture with soil.
In accordance with a further embodiment of the present invention, a horizontal stepped wall forms a supporting surface for an adjacent grid plate which extends over the whole lateral length. By this abutment, which is placed in a vertical stepped wall and which is also placed in the tread, this abutment is held in a fixed and stable manner and at the largest possible distance from the loose ground.
According to yet another embodiment of the present invention, the rib-reinforced bottom side may consist of ring-shaped knots which, by rib-shaped webs, are connected with one another and with the sides. The grid plate may also be designed in the shape of a square.
In accordance with a further embodiment of the present invention, the lateral walls for the wall apertures are also constructed in such a manner that, viewed from both the top and bottom side, they project in the shape of steps. In this embodiment, the vertical stepped-wall parts may be constructed like abutments. The lateral walls of the grid plate, which are provided with double wall apertures and doubly constructed abutments, are constructed for emplacement of the grid plate on both sides. When emplacing the grid plates, it is therefore possible to selectively use the top or bottom side as the treading side of the grid plate. The connecting webs as well as the wall apertures are arranged preferably symmetrically with respect to the center of the grid plate height, so that alternately, the top and the bottom side can be layed in upward direction as the tread.
According to advantageous features of certain preferred embodiments of the present invention, the length of the connecting webs are dimensioned such that the grid plates have a shifting clearance of approximately 10 mm away from one another or toward one another. As a result, it becomes possible to install the grid plates in a flat arc. In addition, possible manufacturing tolerances may be compensated.
Additionally, according to yet another embodiment of the present invention, the lateral walls, in the area of the wall apertures, may project so far that the hooks can lock from above into the free gap.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.